\tracingonline=2
\tracingcommands=2
\tracingmacros=2
\tracingrestores=2

% integer parameter
\showthe\endlinechar
\showthe\escapechar
\showthe\tolerance
\showthe\mag
\showthe\maxdeadcycles

% integer register
\showthe\count0
\showthe\count10

% catcode
\showthe\catcode`a
\showthe\catcode`\\

% errors
% XXX
%\showthe\xx\yy\count0

\end
